O/W wax dispersions and plaster products obtainable from them

ABSTRACT

The invention relates to O/W wax dispersions based on water, an emulsifier and a wax phase containing predominantly aliphatic hydrocarbons and polar compounds having chain lengths of at least 18 carbon atoms, and also plaster compositions comprising the O/W wax dispersion, and the use of the O/W wax dispersion.

The invention relates to aqueous compounds containing waxes and gypsumproducts that can be manufactured from these, particularly aeratedgypsum and plasterboard.

Gypsum is calcium sulphate that can be present with and withoutcrystallisation water. Naturally occurring gypsum rock is calciumsulphate dihydrate (CaSO₄×2H₂O); the anhydrous form of calcium, sulphateis frequently referred to as anhydrite (CaSO₄). In the language of thisapplication, “gypsum” refers to naturally occurring gypsum rock, thecorresponding products of industrial processes and also the productsobtained during the burning of these raw materials.

Gypsum is ideally suited as a construction and working material, due tothe fact that it is easy to dehydrate (dehydration (1)). Dehydration isa reversible process. Exposure to energy drives some or all of thecrystallisation water out of the calcium sulphate dihydrate. The reversereaction after water is added (rehydration (2)) causes the previouslyburned, i.e. at least partially dehydrated gypsum, to become solid,forming a crystalline structure.

(CaSO₄×2H₂O)+T→(CaSO₄×0.5H₂O)+1.5H₂O

(CaSO₄×2H₂O)+T→CaSO₄×2H₂O

Gypsum stone+energy burnt gypsum  (1)

Gypsum stone+energy burnt gypsum  (2)

Naturally occurring gypsum varies in terms of its purity. Naturalimpurities include, e.g. limestone (e.g. muscovite or dolomiteCaCO₃×MgCO₃), marl, mineral clay (e.g. montinorillonite or caolinite),and occasionally also sand, bitumen or a variety of salts. However,gypsum is also accessible from various technical processes. For example,flue-gas or REA gypsum with a high degree of purity is produced duringthe desulphurisation of flue gases.

Gypsum plasterboards are industrially manufactured building boardsessentially made up of gypsum, the surfaces and possibly also thelongitudinal edges of which are surrounded by firmly adhered paperboardto suit the application. The gypsum core surrounded by paperboard maycontain air spaces and additives to achieve given properties.

Essential mechanical plasterboard properties result from the combinedeffect of the gypsum core and the paperboard casing. This involves thepaperboard acting to reinforce the tension area, which in conjunctionwith the gypsum core gives the gypsum plasterboard the required strengthand flexural rigidity. Various types of gypsum plasterboard (GKB) aredistinguished, e.g. those that include additives to delay waterabsorption (impregnated gypsum plasterboard (GKBI) and impregnatedfire-resistant gypsum plasterboard (GKFI)).

The water absorption and drying-out time of gypsum plaster-board istested according to DIN 18180 (2 hours' spent in water).

GKB/GKF GKBI/GKFI Water absorption in (w/w) % 30-50 <10 Drying-out timein hrs 70 15

Gypsum plasterboard is made from gypsum and additives for the gypsumcore, as well as high-grade, repeatedly couched paperboard on large beltsystems running continuously. Plaster of Paris (low-fired gypsum,produced at temperatures of roughly 120° C. to 180° C.) is frequentlyused. The production process comprises the following steps:

-   -   paperboard supplied at the bottom,    -   gypsum slurry supplied and distributed by the moulding station        while paperboard is simultaneously supplied from above to form        the top layer,    -   hardening section,    -   insertion in a dryer (usually after being divided up into        individual boards) and    -   delivery and possible trimming of the transverse edges and        bundling of the boards.

In addition, there are also gypsum building materials in the form ofwallboards made from gypsum, which are briefly referred to as “gypsumwallboards”. These are factory-made building panels made from plaster ofParis and water for non-weight-bearing structural components. Gypsumwallboards may contain fibres, fillers and additive substances, as wellas other additives, and they may be coloured with pigments todistinguish them visually. They have smooth visible surfaces and aredesigned with alternating tongue and groove finishes on the abutting andstorage surfaces. Here, too, water-repellent boards are known.

Board production takes place in largely automated production plants.Uniform, runny slurry is made from plaster of Paris, water and possiblyadditives in a dosage and mixing apparatus and used to fill the mouldingboxes of the gypsum plasterboard machine. Once the mixture has set, theboards are ejected hydraulically and transported to the dryer. This isfollowed by drying in heated continuous driers. After drying, the boardsare combined into packages or loaded onto pallets.

Gypsum fibre boards are furthermore referred to as gypsum-basedplasterboard.

The production of gypsum with low bulk densities, particularly so-calledfoam or aerated gypsum, is the object of many patents and publications.The solutions known hitherto can generally be divided into two groups:

(1) Use of gas formers (propellants), which are added to the bindingagent partially dry or are completely or partially added to the latteronly during the aerated gypsum production process via the mixing water.The gas formers mainly comprise several material components in which achemical reaction is activated by the water coupled with the creation ofa gas. The resulting gas bubbles force the gypsum slurry up in themould.

(2) Undermixing of separately prepared foam, which is added to themixture in the mixer and immediately causes pores to form in the made-upmaterial slurry. Foam is mainly produced by atomising water and airenriched with surface-active substances (surfactants).

It is also known that aerated gypsum elements produced using theaforementioned method are additionally water-repellent. This involveswater-repellent additives being added to the mixer in the mixturepreparation phase.

Gypsum products, particularly gypsum plasterboard, are provided withadditives that delay water absorption, for use in damp areas. Theimpregnating additives are usually added to the gypsum mixture beforethe gypsum products are made and worked into it uniformly, after whichthe gypsum mixtures are usually dried in layers at a high temperature ofe.g. 100 to 150° C. and then cooled. If the gypsum boards are coveredwith paperboard, they are referred to as gypsum plasterboards.

If the gypsum does not receive suitable water-repellent treatment, theeffect of dampness can cause the paperboard to soften, leading todeformation. The use of gypsum plasterboard in damp rooms, such asbathrooms, laundry rooms, etc. is therefore problematic due to itsdiminishing rigidity and deformation. This has particularly seriouseffects when the gypsum plasterboard has ceramic tiles adhered to it,for example. The dampness causes the paperboard to soften, lose itsinner rigidity and split under the weight of the ceramic tiles, causingthe layer of paperboard attached to the boards to fall away. Thedestruction of the remaining gypsum paperboard is then only a matter oftime.

In addition to the diminishing rigidity and deformation, corrosion andmildew can accelerate the destruction. Even the adhesive layer appliedto the entire surface for the ceramic tiles, which usually has asynthetic base, cannot inhibit the effect of the dampness.

The use of silicon or siloxane emulsions/dispersions for impregnation isknown. In addition, dispersions based on paraffin or montan waxes areknown. However, polymers and resins are also used, which do not fallinto the wax category. Polyvinyl alcohols are referred to as polymers.The wax components are in some cases also added to the gypsum mixture inpowder form. Mixtures of asphalt or bitumen dispersions, in some casesused in combination with polyvinyl alcohols, in which a silicon compoundor a synthetic resin emulsion has been added to the gypsum, are likewiseknown from the literature.

However, it is difficult to obtain a satisfactory water-repellent orhydrophobic product, which is sufficiently hydrophobic and, at the sametime, facilitates the necessary foam stability to produce an aeratedproduct.

U.S. Pat. No. 3,935,021 describes a gypsum wallboard in which polyvinylalcohol and a wax-asphalt emulsion are introduced into the gypsum core.Wax-asphalt emulsions are widely used in gypsum wallboards, althoughcertain disadvantages are associated with their use.

In U.S. Pat. No. 5,437,722 an aqueous emulsion is used to make gypsumproducts water-repellent, which comprises a hydrocarbon wax, a montanwax and an emulsifier/stabiliser system with the addition of polyvinylalcohol.

WO 98/09.925 describes an aerated gypsum product, which is madewater-repellent through the inclusion of an aqueous emulsion, whichcomprises a hydrocarbon wax, a montan wax and a colloid-stabilisedemulsifier system.

Other aqueous wax dispersions for making gypsum productswater-repellent, which contain starch, long-chain alkyl phenols,saponified montan waxes, surfactant, complexing agents and paraffinwaxes are known from U.S. Pat. No. 6,585,820. U.S. Pat. No. 6,595,553also mentions surfactant, montan wax and paraffin wax as an integralpart of the aqueous wax dispersion.

The problem addressed by the present invention is that of finding awater-repelling agent that is suitable for both traditional gypsumplasterboard and also for the technically more complex production ofaerated gypsum. A further problem facing the invention is that ofguaranteeing sufficient vapour permeability, despite the water-repellentnature. Furthermore, the wax additive must improve the flow performanceof the gypsum mixture, bring about a slight change in the reinforcingbehaviour of the gypsum, cause a significant improvement in thepaperboard adhesion and have a very slight effect on foaming in theprocess.

The effectiveness of wax dispersions in gypsum products is cruciallydependent on the composition. It is obviously important for the internalsurface of the micropores to be sealed in the gypsum. On the other hand,the pores must not be completely closed off, in order to retain thedesired vapour permeability. This cannot be achieved with purehydrocarbon dispersions according to our findings. In the past, montanwax was used here in the mixture with paraffin. Montan wax is a hardfossil wax of vegetable origin, which has survived the carbonisationprocess virtually unchanged. It therefore occurs in some brown coal asan extractable element. Important chemical parameters include the acidnumber (AN) and saponification number (SN) of the montan wax.Furthermore, a small number of hydrocarbons are contained in montanwaxes, but not unsubstantial proportions of montan resins and asphaltsubstances, whereby the latter contain a not unsubstantial proportion ofinorganic ash components (0.4 to 4% by wt.).

Montan resins and ash components may affect the colour if, for example,a particularly light-coloured gypsum is required when the material isused in visible construction work. The hydrocarbon chains in the waxacids and wax alcohols have a chain length of 20 to 34 C units with amaximum of around 30 C units. In this case, the focus lies on chainswith a straight-line number of carbon atoms.

When using wax dispersions in impregnated gypsum plasterboard (GKBI) andimpregnated fire-resistant gypsum plasterboard (GKFI), it is generallyof particular significance that these do not have a negative effect onthe paperboard's adhesion to the surface of the gypsum core.Furthermore, the emulsifier systems must also be based on optimumadhesion of the paperboard layer and minimum interference with thefoaming behaviour of the gypsum slurry. Surprisingly, it was found thatthe water-repelling effect in gypsum products known hithertopredominantly from wax dispersions containing montan wax can also beachieved with other specially selected polar synthetic and naturalcomponents. Apart from paraffin, longer-chain alphaolefins (hydrogenatedand/or not hydrogenated) and Fischer-Tropsch waxes can also be used asthe basic wax phase. Also capable of being used in the composition arenatural waxes, fats, fatty alcohols and synthetic and syntheticallymodified natural resin components.

It emerged that the desired water-repellence could also be achieved withthe help of wax phases without montan wax. In this case, other waxphases and also other polar additives were identified as useable. Thisproduces lighter/whiter gypsum products that can also be used forvisible construction, as the wax phases, particularly the additivesused, display significantly lower ash contents or none at all and alsocontain no dark asphalt and resin components.

The O/W wax dispersion according to the invention for use in gypsumproducts consist of:

-   -   at least 30% by wt., particularly 30 to 80% by wt., preferably        around 40 to 65% by wt., water,    -   at least 20% by wt., particularly 70 to 20% by wt., preferably        35 to 60% by wt, wax phase as the disperse phase, wherein the        wax phase or the total substances used to create the wax phase        (i.e. before further saponification, where appropriate, through        optional alkalisation or the alkali/earth alkali addition)        display a saponification number greater than 0.2 mgKOH/g,    -   at least 0.1% by wt., particularly 0.5 to 5% by wt., of an        emulsifier or thickening agent as the dispersal agent, and    -   maximum 20% by wt., particularly under 10% by wt., other        substances, particularly as a component of the continuous phase,        wherein the wax phase consists of the following, each based on        the wax phase:

-   (a) 50 to 98% by wt. aliphatic hydrocarbons (HC) or an HC mixture,    each with a solidification point above 50° C. and below 95° C.,    particularly 55 to 80° C.,

-   (b) 2 to below 50% by wt., particularly 5 to 20% by wt., from polar,    long-chain compounds with chain lengths of at least 18 carbon atoms,    particularly aliphatic, containing    -   at least one carboxyl group, possibly    -   partially or fully derivated,    -   an ether group and/or    -   at least one hydroxyl group (—OH)    -    per molecule, but no more than three of the afore-mentioned        groups together, particularly polar, long-chain compounds, which        contain per molecule at least one carboxyl group, possibly        partially or fully derivated, alongside possibly up to two other        groups per molecule, including the carboxyl group, possibly        derivated,        and possibly

-   (c) maximum 10% by wt., particularly below 5 and preferably below    0.5% by wt., other substances solid at room temperature,    particularly aromatic-free, or none and

-   (d) maximum 3% by wt. substances liquid at room temperature (at room    temperature and normal pressure), particularly below 1.5% by wt.

Advantageous embodiments are the subject of the dependent claims or aredescribed below. Also claimed are gypsum compositions, as describedabove, containing wax dispersions and the use of wax dispersions in suchgypsum compounds or else the gypsum products described above.

Substances that can be used as aliphatic hydrocarbons according to theinvention are paraffin, synthetic Fischer-Tropsch waxes and alphaolefins(AO, hydrogenated and not hydrogenated) with a solidification point ofover 50° C. and below 95° C. and, particularly, with average C chainlengths greater than 25 in each case.

Polar compounds within the meaning of the present invention arecompounds displaying hydrocarbon chains with per molecule over 18 Catoms and at least one hydroxyl group, an ether group and/or a carboxylgroup (—C(═O)O—), possibly also derivated, i.e. esterified orsaponified. The polar compounds preferably display no more than three ofthe aforementioned groups or a total of three polar groups, particularlyone or two groups, per molecule overall.

The polar compounds may be oxidised and possibly also partiallysaponified Fisher-Tropsch waxes, oxidised paraffin, oxidisedpolyethylene, so-called PE wax esters (jointly referred to as oxidisedhydrocarbons (HC) or partially saponified oxidised HC's) and modifiednatural and/or synthetic resins, as well as natural waxes such asbeeswax and, in particular, carnauba wax. Furthermore, fats(triglycerides), e.g. of vegetable origin, such as palm, soya andrutabaga fats, are suitable. The acid groups contained in the polaradditives may be saponified during the course of the wax dispersionproduction with the aid of alkaline substances (e.g. potassium orcaustic soda). These lyes are preferably overdosed in this case, so thatpH values of over 11 are obtained. This also has a favourable effect onthe resistance of the wax dispersions to biological decomposition andmildew. Synthetically modified, particularly esterified, colophoniumresins (colophony) such as glycerine and/or pentaerythrite maleic acidcolophonium resins, preferably combined particularly with oxidised HC'sand/or partially saponified oxidised HC's are also suitable.

It is particularly preferable for the wax dispersion to contain carnaubawax as a constituent part of the polar compounds, particularly at 1 to20% by wt., particularly 1 to 15% by wt., relative to the wax phase.

Particularly advantageous are mixtures of polar compounds, which containas polar compounds the above oxidised hydrocarbons (HC) or partiallysaponified, oxidised HC's (greater than 1% by wt.) and carnauba wax(greater than 1% by wt.) or the above oxidised hydrocarbons (HC) orpartially saponified, oxidised HC's (greater than 1% by wt.) and theabove synthetically modified colophonium resins or aliphatic hydrocarbonresins (greater than 1% by wt.). The percentages by weight each relateto the wax phase (=100% by wt.).

The water-repellent effect is reinforced if the polar compounds containas the predominant constituent part oxidised and possibly also partiallysaponified Fischer-Tropsch waxes, oxidised paraffin, oxidisedpolyethylene, so-called PE waxes and, as the lesser component, fats(e.g. palm fats or soya oils) and/or fatty alcohols (e.g. Nafol® 20+).This produces synergistic effects. In other words, the reduction inwater absorption when additives are combined increases even more thancan be expected from the sum of the individual effects.

In this case, the wax phase is preferably added to the gypsum slurry inthe form of an aqueous wax dispersion, as gypsum board production iswater-based and the dosing of the wax phase can therefore besignificantly more accurate. Furthermore, the preferably small particlesize of the disperse wax phase (average particle size less than 2 μm andparticularly roughly 1 μm) ensures a particularly uniform distributionof the active substance in the gypsum slurry.

In principle, all types used for the production of wax dispersions, i.e.non-ionic, anionic and cationic emulsifier types, but also combinationsof these (non-ionic with anionic and non-ionic with cationic) aresuitable as emulsifiers. Non-ionic and anionic emulsifiers areparticularly suitable. Furthermore, emulsifiers that achievestabilisation by concentrating the water phase are also suitable. Thesemay be natural resins, for example, (Gum Ghatti, derivated cellulose) orxanthane polymers or else polysaccharide, but also inorganic substancesof the bentonite type. Particularly suitable as emulsifiers aresulphonates such as naphthaline sulphonate and/or lignin sulphonate,preferably along with a thickening agent such as Gum Ghatti, inparticular.

Furthermore, polyvinyl alcohols may be added to the wax dispersion,particularly up to 0.5 to 4% by wt. relative to the wax dispersion,which are available, for example, as partially hydrolised ethylene vinylacetate polymers, but also produced from acrylates and other polyvinylesters. Degrees of hydrolysis of over 70%, particularly over 85%, aredesirable, but not a requirement.

The compositions according to the invention are advantageously waxdispersions, which can be produced with the aid of homogenisers. In thiscase, at least two phases are combined with one another (pre-emulsion).

At least the wax-containing phase is heated above the solidificationpoint for this, in order to melt the wax. The other phase is the aqueousphase. This is preferably mixed with the emulsifier and isadvantageously heated likewise.

The pre-emulsion is then passed through the circuit e.g. via splittinghomogenisers, until the desired particle size of the wax phase isachieved. The emulsion is then cooled to temperatures below thesolidification point of the wax phase. The individual wax particles ofthe disperse phase are evenly distributed in the aqueous, continuousphase by the process and a wax dispersion with prolonged stability isthereby obtained. The wax dispersion is thereby created. This is an oilin water (O/W) wax suspension with an average particle diameter ofparticularly 0.1 to 10 μm, advantageously 0.5 to 2 μm. The waxdispersion according to the invention is particularly suitable for theproduction of the water-repellent gypsum compositions described above,particularly those containing or comprising foamed gypsum or aeratedgypsum and, in particular, coated gypsum plasterboard, preferably usingthe aforementioned gypsum.

FIG. 1 shows how the O/W emulsions are typically produced. In a waxboiler (1) fitted with a temperature sensor and temperature monitoringsystem, the wax emulsifier (2), water and hot steam (3) are produced,agitated and moved into the pre-emulsion boiler (4) by means of a pump(5), where the water-emulsifier mixture (6) is added. Delivery andtransfer into the homogeniser (8) takes place using the pump (7). Bymeans of a cooling medium (9), the temperature of the emulsion islowered in the cooling system (10), e.g. to 30° C., in order to obtainthe finished wax dispersion (11).

EXPERIMENTS

The degree of water repellence can be determined by subjecting thegypsum body to an immersion test. This involves the water absorptionbeing determined in % by wt. after a 120 minute immersion period (H₂O120 mins column in the following table). Suitable threshold values inthis case are <10% by wt. and, particularly, <5% by wt. waterabsorption.

Table 1 shows the data for the finished wax phases (% stands for % bywt. in each case). It emerges that predominantly hard wax phases (needlepenetration at 25° C.<20 [0.1 mm] in accordance with ASTM D1321) withsolidification points of between 60 and 80° C. and also acid numbers(DIN 51558) of between 0 and 10 (mgKOH/g) and also saponificationnumbers from 0 to 20 mgKOH/g have a beneficial effect on waterrepellence. This produces the values required by DIN 18180 of <10% bywt. water absorption. The water absorption is therefore significantlyreduced compared with the blind value (31%) of the natural gypsum usedin this case, which demonstrates the effect of the wax mixtures used aswax dispersions. The wax dispersions (WD) were made according to thefollowing suggested formulation:

60% by wt. water; 3% by wt. Marlophen® NP 10 (non-ionic surfactant fromSasol Olefins and Surfactants GmbH on an ethoxylate base); 1% by wt. KOH(45% by wt.) and 36% wax phase.

Laboratory Production of the Wax Dispersion:

The water was heated to approx. 80° C. along with the surfactant and theKOH and agitated for roughly 20 mins. The molten (80-100° C.) wax phasewas then added and agitated for a further 5 minutes. The pre-emulsionwas added to the homogeniser and passed through the circuit for 1minute, after which it was homogenised for 1 minute at a pressure ofroughly 200 bar. The wax emulsion was then cooled to room temperatureduring which the wax particles solidified and the wax dispersion wasproduced.

TABLE 2 Substances used Name Type Manufacturer Paraffin Sasolwax 6403(Fully Paraffin) Sasol Wax GmbH EP 64/66 Carnauba wax Natural palm waxKahl & Co Resin Escorene 1102 F, aliphatic Exxon Mobil hydrocarbon resin

Key to Table 1

(*) Blind value of the untreated natural gypsum 31%

(**) These two dispersions serve for comparison purposes with the stateof the art

(1) Solidification point ASTMD 938

(2) Needle penetration ASTM D 1321 at 25° C.

(3) Acid number according to DIN 51558

(4) Saponification number according to DIN 51559

(5) Water absorption according to DIN 81180

(6) Internal house methods

+ better than blind value (possibly better than gypsum value by howmuch)

= equal to blind value—not measured

TABLE 1 Properties of different wax dispersions Data Foam H₂O PaperStart of End of Flow PenN25 AN SN reduction 120 min adhesion hardeninghardening measure EP (1) (2) (3) (4) (5) (6) (6) (6) (6) Compositionunit No. Dispersion (° C.) (0.1 mm) (mgKOH/g) (% by wt.) Min (*) *Gypsum blind value 31 = 6 9 = VI * Montan wax/paraffin 70.5 10 3 8.7 =2.4 + +2 +4 Higher ** V2 Montan wax/paraffin 64.5 11 3.1 9 = 2.5 + +2 +4Higher ** 1 Carnauba wax/ 66 16 0.3 1.4 = 2.3 + = +4 Higher paraffin(2.5% carnauba) 2 Carnauba wax/ 65 11 0.5 4.1 Smaller 4.6 + +2 +2 =paraffin (5% carnauba) 3 Carnauba wax/ 67 11 1 8.2 = 3.6 + = +4 Thickerresin/paraffin (10% carnauba, 5% escorez) 4 Carnauba wax/ 66 19 1 8.2 −6 − − − − paraffin (10% carnauba wax)

1. An O/W wax dispersion comprising: at least 30% by wt. water, at least 20% by wt. wax phase as the disperse phase, wherein the wax phase or all of the substances used to create the wax phase have a saponification number greater than 0.2 mgKOH/g, at least 0.1% by wt. of an emulsifier or thickening agent as dispersing adjuvant, and wherein the wax phase comprises the following, based on the wax phase: (a) 50 to 98% by wt. aliphatic hydrocarbons (HC) or mixtures thereof, each with a solidification point above 50° C. and below 95° C., (b) 2 to below 50% by wt. from polar, long-chain compounds with at least 18 carbon atoms, containing at least one carboxyl group, optionally partially or fully derivated, and/or an ether group and/or at least one hydroxyl group (—OH)  per molecule, but no more than three of the afore-mentioned groups together, and optionally a maximum of 20% by wt. other substances wherein (c) a maximum of 10% by wt. of said other substances are solid at room temperature and (d) a maximum of 3% by wt. of said other substances are liquid at room temperature, wherein the wax phase comprises carnauba wax, esterified colophonium resins and/or beeswax and the wax dispersion has a pH value greater than
 11. 2. (canceled)
 3. The wax dispersion according to any one of claims 1 or 25, characterised in that over 0 to 10% by wt., particularly 1 to 3% by wt., water-soluble alkaline substances, optionally at least partially bound through the saponification of acid groups, are contained or added.
 4. The wax dispersion according to any one of claims 1 or 25, characterised in that the HC's are selected from: petroleum paraffin (PP) with over 25 carbon atoms on average, synthetic alphaolefins (hydrogenated or not hydrogenated) (AO) with over 30 carbon atoms on average, Fisher-Tropsch (FT) waxes with over 25 carbon atoms on average and mixtures thereof.
 5. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase or the total substances used to create the wax phase has a saponification number of 0 to 40 mgKOH/g, particularly 0 to 7 mgKOH/g, before the possible (further) saponification or (further) alkali/earth alkali addition.
 6. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase or the total substances used to create the wax phase has a saponification number of over 0.2 to 120 mgKOH/g, particularly 1 to 20 mgKOH/g, before the possible (further) saponification or (further) alkali/earth alkali addition.
 7. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase has a colour number below 0.5 (according to ASTM D 1500).
 8. The wax dispersion according to any one of claims 1 or 25, characterised in that the polar compounds are oxidised HC's, comprising oxidised FT and/or polyethylene types and/or ethers, alone or in mixtures, particularly oxidised HC's and/or partially saponified oxidised HC's or mixtures of carnauba wax and oxidised HC's, optionally each saponified.
 9. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase has a solidification point of over 55° C. to 95° C., preferably 62° C. to 80° C.
 10. The wax dispersion according to any one of claims 1 or 25, characterised in that the proportion of HC's being linear is greater than 50% by wt., particularly greater than 65% by wt.
 11. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase has a pH value of 11 to
 13. 12. The wax dispersion according to any one of claims 1 or 25, characterised in that the particle/droplet diameter of the disperse phase is 0.1 to 10 μm, advantageously from 0.5 to 2 μm.
 13. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase has a needle penetration value from 7 to 17 (according to ASTM D 1321) at 25° C.
 14. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax dispersion has a Brookfield viscosity at 25° C. (ASTM D 2983) of under 2000 mPas/s.
 15. The wax dispersion according to any one of claims 1 or 25, characterised in that the polar, long-chain compounds are aliphatic.
 16. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase contains less than 5% by wt. and particularly less than 0.5% by wt. other substances that are solid at room temperature, the O/W wax dispersion preferably contains no other solid substances at room temperature.
 17. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax phase contains under 0.2% by wt. substituted phenols, such as alkyl phenols, preferably none.
 18. The wax dispersion according to any one of claims 1 or 25, characterised in that the polar compounds comprise carnauba wax, particularly 1 to 20% by wt. relative to the wax phase.
 19. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax dispersion comprises polyvinyl alcohols, particularly 0.5 to 4% by wt., optionally partially hydrolised (over 70%).
 20. The wax dispersion according to any one of claims 1 or 25, characterised in that the polar compounds comprises esterified colophonium resins, beeswax and/or carnauba wax and/or mixtures of these, optionally each partially saponified.
 21. The wax dispersion according to any one of claims 1 or 25, characterised in that the wax dispersion contains less than 5% by wt., particularly less than 2% by wt., montan waxes relative to the wax phase in each case, preferably none.
 22. (canceled)
 23. A gypsum composition containing over 50% by wt., particularly 50 to 70% by wt. gypsum, relative to calcium sulphate dihydrate, optionally hydrated, and 0.1 to 5% by wt., preferably 0.5 to 2.5% by wt., of the wax dispersion of claim
 1. 24. The gypsum composition of claim 23, characterised in that the gypsum composition contains less than 5% by wt., particularly less than 2% by wt., montan waxes, relative to the wax phase in each case, preferably none.
 25. A method of obtaining a wax dispersion comprising: combining at least 30% by wt. water with at least 20% by wt. wax phase as the disperse phase, wherein the wax phase or all of the substances used to create the wax phase have a saponification number greater than 0.2 mgKOH/g, and wherein the wax phase comprises the following, based on the wax phase: (a) 50 to 98% by wt. aliphatic hydrocarbons (HC) or mixtures thereof, each with a solidification point above 50° C. and below 95° C., (b) 2 to below 50% by wt. from polar, long-chain compounds with at least 18 carbon atoms, containing at least one carboxyl group, optionally partially or fully derivated, and/or an ether group and/or at least one hydroxyl group (—OH)  per molecule, but no more than three of the afore-mentioned groups together, and at least one emulsifier to form a mixture; homogenizing the mixture, wherein the wax phase liquefies as a result of temperature rise during homogenization; and cooling the homogenized mixture to solidify at least a part of the mixture. 